Laminate pressure containing body for a well tool

ABSTRACT

Apparatus if provided for use in wells, particularly wells that have high-pressure and high-temperature conditions in the well. The shells of completion equipment that is required to withstand the rigorous conditions in such wells are increased in strength by laminate layers that are formed of materials having higher yield strength than the yield strength of materials that can be used in well fluids.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to apparatus for use in wells. Moreparticularly, pressure-containing apparatus is provided for use inhigh-pressure, high-temperature wells where wall thickness of apparatusis to be minimized and material selection is limited by well conditions.

2. Description of Related Art

With energy prices at all time highs, companies involved in thediscovery and production of hydrocarbons are pursuing deeper offshoreoil and gas plays. As well depths increase, well architecture becomesmore challenging. Geologists, geophysicists and petroleum engineersunderstand that as well depths increase, so does formation pressure andtemperature. It is estimated that pressures of 30,000 psi and 500 deg F.and beyond may become commonplace in future wells. The industry acronymfor High-Pressure and High-Temperature wells is HPHT. As HPHT conditionspresent themselves in deep wells, the equipment needed to safelycomplete and produce HPHT wells must be developed to withstand safelythe rigors of these extreme conditions.

Industry is developing methods and materials to drill the HPHT wellssafely, but technology gaps in equipment placed in the wells forproducing the wells, called “well completion equipment,” also must beaddressed. This includes, but is not limited to devices that arenormally larger diameter than the tubing, such as subsurface safetyvalves, packers, flow control devices (e.g., sliding sleeves), tubinghangers, on-off attachments, and gas lift or instrument mandrels as wellas equipment normally the same diameter as tubulars that wouldpreferably be smaller in diameter, as least in some segments of a well,such as production tubing, liners, expansion joints and theirconnectors. Several papers have been published recently addressing anddiscussing “gaps” in current technology (for examples, “Ultra Deep HPHTCompletions: Classification, Design Methodologies and TechnicalChallenges, OTC 17927, Offshore Technology Conference, Houston, Tex.,May. 2006; “HPHT Completion Challenges,” SPE 97589, Society of Pet.Engrs., May, 2005).

Substances present in fluids produced from HPHT wells are oftendetrimental to materials that form tubulars and well completionequipment. One of the worst substances is hydrogen sulfide (H₂S), whichcan cause stress corrosion cracking, especially of materials that havehigh yield strength. Another substance that is often present in HPHTwells is carbon dioxide (CO₂), which can cause weight loss corrosion.The National Association of Corrosion Engineers (NACE) has developedguidelines for selecting materials that can be used in the presence ofadverse wellbore chemistry. Most often these “NACE materials” fall inthe mid-range of material hardness and yield strength.

Additionally, there is recognition among mechanical engineers thatguidelines and practices for the safe design of equipment at 15,000 psiand 300° F. are vastly different for the requirements of 30,000 psi and500° F. As an outgrowth of this knowledge, The American PetroleumInstitute (API) is in the process of adopting the requirements of ASMESection VIII Division III into the design requirements of downholeequipment. Section VIII Division III practice requires that Ultra HighPressure Vessels have the allowable stress on materials de-rated as aresult of temperature and that a fracture analysis be performed as apart of the design realization process. The simply stated result is thatthe wall thickness of pressure-containing devices must be very thick ifhomogeneous NACE materials are used in downhole pressure-containingvessels.

When drilling a well, costs are much higher as depth increases. Asimilar relationship exists with the diameter of the hole being drilled.Larger diameter, deeper holes become prohibitively expensive unlessproduction flow area (inside diameter of the production tubing) ismaximized. Operators want the largest possible flow area in the smallestpossible hole. The economic viability of a project is determined by theflow rate from the well. For deep, expensive wells, the production flowarea (diameter of the tubing) must often be 5½-in, 7-in, or in somecases 9⅝-in. The design of the well must have its genesis at the insidediameter of the production tubing and work outward to determine whatdiameter hole must be drilled.

These factors serve to work against each other in the followingsummarized manner. Wellbores must be deeper to reach pay zones.Production flow areas must be maximized and the hole diameter must beminimized for the well to be economic. The cost of drilling a well ismuch more expensive as the diameter and depth each increase. Materialsmust be tailored to the environment, but use of the strongest materialsmay be inadvisable or prohibited due to NACE requirements to avoidchemical attack. Design practices require thicker and thicker walls toaccommodate these factors. Smaller drilled holes, bigger flowing bores,and thicker wall requirements are conflicting requirements.

What is needed is the development of a pressure-containing body thatminimizes wall thickness, uses NACE materials where exposed toproduction fluids, fits in the smallest possible drilled and cased hole,and yields the largest possible flow area for the well. Use of such abody or device can significantly improve the economic viability of newwells.

SUMMARY OF THE INVENTION

Apparatus is provided for allowing greater flow area in wells bystrengthening pressure-containing shells or tubulars that are a part ofcompletion equipment in the wells. Laminate layers made of materialshaving higher yield value than equipment that comes in contact with wellfluids are added to completion equipment. The layers may be formed ofcylinders, wound wire or other forms of materials. Metal matrixcomposite materials may be used.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-section view of a shell for completion equipmentattached to tubing in a well showing one embodiment of laminate layersover the shell.

FIG. 2 is a cross-section view of a shell for completion equipmentattached to tubing in a well showing another embodiment of laminatelayers over the shell and a feed-through tube in the laminate layers.

FIG. 3 is a cross-section view of a tubular for completion equipmentshowing an embodiment of laminate layers over the tubular.

DETAILED DESCRIPTION

The description herein applies the invention primarily to a genre ofwell tools known as well completion tools or equipment. Generally, theinvention applies to equipment in a well for which less wall thicknessis needed. This would include: pressure-containing equipment in a wellthat must, because of its inherent design, have greater outside diameterthan the tubing in a well if it is to maintain the same flow area as thetubing, and tubulars or connectors for tubulars that preferably arereduced in external diameter with the same internal diameter. Thisincludes, but is not limited to, devices that are normally largerdiameter than the tubing, such as subsurface safety valves, packers,flow control devices (e.g., sliding sleeves), tubing hangers, on-offattachments, and gas lift or instrument mandrels as well as equipmentnormally the same diameter as tubulars that would preferably be smallerin diameter, as least in some segments of a well, such as productiontubing, liners, expansion joints and their connectors. One of ordinaryskill in the art may immediately be able to apply this invention toother downhole devices, such as drilling equipment; any such uses of thepresent invention in wells is considered within the scope and spirit ofthe present invention.

FIG. 1 illustrates the invention by showing a shell for completionequipment having a diameter greater than the diameter of tubing in awell. Well 10 has been drilled in the earth, casing 12 has been placedin the well and cement 14 has been placed in the annulus outside thecasing. The diameter of the hole of well 10 has been selected to allowan acceptable thickness of cement 14 and outside diameter of casing 12.The wall thickness of casing 12 has been determined by the design burstand collapse strength of the casing and the inside diameter of casing 12has been determined by the diameter of tubing 15 that is needed in thewell and the size of any pressure-containing completion equipment thatmay be placed in the tubing. FIG. 1 simply shows sub 16, whichgenerically represents the shell for completion equipment that must havea larger outside diameter than the diameter of tubing 15 whilemaintaining a larger inside diameter for containing completionequipment. Upper flow wetted body 17 connects to lower flow wetted body18, forming joint 19 of sub 16. Pressure seal 20 is provided. This sealmay be all-metal, elastomeric, thermoplastic, spring energized, in aconcentric configuration (shown) or it may be a face seal (not shown).Upper body half 17 and lower body half 18 may be separated at joint 19to allow inclusion of the functional portion of completion equipment.The present invention may be employed when no joint 19 is required (notshown), a single joint 19 is required, or when a plurality of joints isrequired. Joint 19 may contain threads for connecting or be joined bywelding, for examples.

After assembly of sub 16, first sleeve 22 is arranged to slide over andcover the larger outside diameter of sub 16. First sleeve 22 may becold-worked in place. Depending on the service requirements, a preferredembodiment is pressed fit, whereby the outside diameters of upper flowwetted body 17 and lower flow wetted body 18 are larger than the insidediameter of first sleeve 22 and may be tapered. In this instance, firstsleeve 22 is placed under a large axial load, which causes it to deformradially outward and expand over the larger outside diameters of upperflow wetted body 17 and lower flow wetted body 18. In an alternativeprocedure, first sleeve 22 is heated to cause expansion and placed overbodies 16 and 17 while hot. First sleeve 22 then acts as an elasticband, placing compressive stress on the upper flow wetted body 17 andthe lower flow wetted body 18. First sleeve 22 may be a higher yieldstrength non-NACE material, or a material with a higher elastic modulus,such as titanium. The net effect is a higher burst pressure for thelaminate body than it would be if the wall thickness were a homogenousNACE material. Sufficient internal pressure exerted inside the well toolplaces upper flow wetted body 17 and lower flow wetted body 18 intension in the radial direction, which is counteracted by thecompressive forces exerted by first sleeve 22. First nut 24 may bethreaded onto first sleeve 22 to retain it. In this configuration,tubing tensile forces are borne by first nut 24, but if upper flowwetted body 17 and lower flow wetted body 18 are threaded together,tubing tensile forces would be primarily borne there. The additionallaminate layers, if confined in the axial direction so as to assume anaxial load, are intended to increase the axial strength within thetensile limits of the outer layers. If ceramic or other high-strengthfibers are used in additional layers, this increase could besignificant.

In the transitional section where flow area is changing, wall thicknessof bodies 17 and 18 may be adjusted in response to stress analysis,which may be performed using well-known finite element procedures, andwhich may include the effect of outer laminate layers. Such analyses maybe substantiated by well-known techniques using strain gauges.

Second sleeve 26 (or subsequent sleeves), having second nut 28, may alsobe used to further strengthen the assembly by adding laminate layers,each with its own beneficial material properties.

First sleeve 22 may be a series of rings arranged longitudinally alongthe body that would yield the same effect on burst strength of the body.Additionally, the first sleeve may take the form of a helix or helicalstrip wrapped around upper flow wetted body 17 and lower flow wettedbody 18. These and other uses of the lamination effect by one of normalskill in the art should be considered within the scope and spirit of thepresent invention.

In operation, the composite wall thickness of upper flow wetted body 17and lower flow wetted body 18, first sleeve 22 and second sleeve 26 orany subsequent sleeves is thinner than if the design engineer chose ahomogenous commercially available NACE material. This allows a greaterflow area in any given well (or casing) size.

FIG. 2 depicts an alternate embodiment of the invention disclosedherein. Sub 30 is attached on both upper and lower ends to productiontubing 15. Sub 30 includes larger internal diameter for completionequipment, as described and shown in FIG. 1. Upper flow wetted body 34connects to a lower flow wetted body 36, forming joint 38. Pressure iscontained by seal 39. This seal may be all-metal, elastomeric,thermoplastic, spring energized, in a concentric configuration (shown)or it may be a face seal (not shown). Upper and lower body halves aredepicted, so as to facilitate or incorporate the inclusion of thefunctional portion of completion equipment, be it a packer, subsurfacesafety valve, or other equipment. The present invention may be employedwhen no joint 38 is required (not shown), a single joint 38 is required,or if a plurality of joints such as joint 38 are required.

After assembly of sub 30, wire wraps 40 may be wound over sub 30.Depicted in FIG. 2 is round wire, but square wire may also be used, andin many instances, may be preferable. Wire may have much higher yieldstrength than wrought material. Higher strength material alone adds tothe allowable stress the body could withstand. There is anothersignificant advantage to the use of wire. The wire may be wrapped undertension, preferably at a tension that is close to the yield strength ofthe wire. Multiple wraps of wire around the upper and lower body halvesof sub 30 may put a very high compressive force on sub 30. Sufficientinternal pressure exerted inside the well tool may place upper flowwetted body 34 and lower flow wetted body 36 in tension in thecircumferential direction, which is counteracted by the compressiveforces exerted by the first sleeve. In another embodiment, a compositematerial may be formed. A metal matrix composite may be utilized togreatly increase burst resistance of relatively thin shells. Compositemay be formed of a ceramic fiber or monofilament that is first woundover the flow wetted body to have a structure as shown in FIG. 2, wherethe fiber is now illustrated at 40. Molten metal 40A may then beinjected into a mold to form a metal matrix over the ceramic fiber. Thisprocedure can result in a composite material that is many times strongerthan the NACE-approved material of the flow wetted body. The assemblycan then be post-cast heat treated to return the body to NACEspecifications. Ceramic fiber is available from 3M Company of St. Paul,Minn. and other sources,

These embodiments mean that a very high internal pressure may be appliedto counteract the “pre-loaded” collapse force induced by the wire (orceramic) wraps, to take the body to a neutrally stressed state. Theresult is a much higher internal pressure (or burst pressure) can beborn by the well apparatus of the present invention before permanentdeformation or failure due to overstress.

Second sleeve 50 (FIG. 2) (or subsequent sleeves) may also be used tofurther strengthen the assembly by adding laminated layers, each withits own beneficial material properties. Second nut 52 may be threadedinto second sleeve 50 to retain it. In this configuration, tubingtensile forces may be borne by second nut 52, but if upper flow wettedbody 34 and lower flow wetted body 36 are threaded together, tubingtensile forces would be primarily borne there.

The shell that encloses well completion equipment normally has a largerdiameter than the tubing that conveys it into the well. FIG. 1 and FIG.2 show this relationship. Annulus 60 is formed outside the shell ofcompletion equipment and any laminate layers on the shell and inside thecasing. Often in multilateral wells umbilicals or control lines (notshown) need to pass through annulus 60. As wall thickness requirementsincrease with pressure and temperature, annulus 60 may become too smallfor well umbilicals or control lines to pass, even with a laminatestructure as disclosed herein. In another embodiment (FIG. 2), wherein ahollow cylinder or multiple wraps of wire or fiber are used, smalldiameter “feed through” tubing 62 may be adapted to the assembly andplaced in a rounded groove in sub 30 or placed adjacent sub 30 prior tobeginning the wrapping operation. This would allow feed through 62 to bedirected through the body with minimal effect on the pressure-retainingproperties of the apparatus.

When smaller outside diameter of a tubular or a connector for a tubularis needed without decreasing inside diameter, the methods describedabove may be employed. FIG. 3 illustrates the application of firstlaminate layer 72 and second laminate layer 74 to tubular 70, which isillustrated with threads for connecting to well tubing 75. Tubular 70may be production tubing, a liner, an expansion joint and the connectorsfor any of these, for example. Various laminate layers as describedabove may be similarly applied to tubular 70 or to a connector fortubular 70. A feed-through tube such as shown in FIG. 2 may be includedin a groove in tubular 70 and under first laminate layer 72.

Although the present invention has been described with reference tospecific details, it is not intended that such details should beregarded as limitations on the scope of the invention, except as and tothe extent that they are included in the accompanying claims.

1. A pressure-containing apparatus for a well, comprising: a shelladapted to be connected to a well tubing and adapted to enclose wellcompletion equipment and having a bore therethrough, the shell beingformed of a material having a yield strength; and a first laminate layercontacting an outside surface of the shell, the first laminate layerbeing formed of a material having higher yield strength than the yieldstrength of the material forming the shell, so as to increase thepressure-containing ability of the shell.
 2. The pressure-containingapparatus of claim 1 further comprising a second laminate layercontacting an outside surface of the first laminate layer to furtherincrease the pressure-containing ability of the shell.
 3. Thepressure-containing apparatus of claim 1 wherein the first laminatelayer comprises a cylinder or a row of wire wound over the shell.
 4. Thepressure-containing apparatus of claim 2 wherein the second laminatelayer comprises a cylinder.
 5. The pressure-containing apparatus ofclaim 2 wherein the second laminate layer comprises a row of wire woundoutside the first laminate layer.
 6. The pressure-containing apparatusof claim 1 wherein the material of the first laminate layer comprises ametal matrix composite.
 7. The pressure-containing apparatus of claim 2wherein the first or the second laminate layer comprises a metal matrixcomposite.
 8. The pressure-containing apparatus of claim 1 wherein theshell includes a section having a transition in flow area therein andthe section includes an area of increased wall thickness in the shell.9. The pressure-containing apparatus of claim 1 wherein the laminatelayer further comprises a nut to provide an axial force from thelaminate layer when the shell is subjected to an axial tension force.10. The pressure-containing apparatus of claim 1 further comprising afeed-through tubing.
 11. The pressure-containing apparatus of claim 2further comprising a feed-through tubing.
 12. The pressure-containingapparatus of claim 1 wherein the shell is adapted to enclose wellcompletion equipment selected from equipment consisting of a subsurfacesafety valve, a mandrel of a packer, a device for controlling flow inthe wellbore, a sliding sleeve, a tubing hanger, an on-off attachment, agas lift mandrel or an instrument mandrel.
 13. A pressure-containingapparatus for a well, comprising: a tubular adapted to be connected to awell tubing and having a bore therethrough, the tubular being formed ofa material having a yield strength; and a first laminate layercontacting an outside surface of the tubular, the first laminate layerbeing formed of a material having higher yield strength than the yieldstrength of the material forming the tubular, so as to increase thepressure-containing ability of the tubular.
 14. The pressure-containingapparatus of claim 13 further comprising a second laminate layercontacting an outside surface of the first laminate layer to furtherincrease the pressure-containing ability of the shell.
 15. Thepressure-containing apparatus of claim 13 wherein the first laminatelayer comprises a cylinder or a row of wire wound over the shell. 16.The pressure-containing apparatus of claim 14 wherein the secondlaminate layer comprises a cylinder.
 17. The pressure-containingapparatus of claim 14 wherein the second laminate layer comprises a rowof wire wound outside the first laminate layer.
 18. Thepressure-containing apparatus of claim 13 wherein the material of thefirst laminate layer comprises a metal matrix composite.
 19. Thepressure-containing apparatus of claim 14 wherein the first or thesecond laminate ayer comprises a metal matrix composite.
 20. Thepressure-containing apparatus of claim 13 further comprising afeed-through tubing.
 21. The pressure-containing apparatus of claim 14further comprising a feed-through tubing.
 22. A method for making apressure-containing apparatus for a well completion equipment,comprising: providing the well completion equipment; providing a shelladapted to be connected to a tubing and adapted to enclose the wellcompletion equipment and having a bore therethrough, the shell beingformed of a material having a yield strength; providing a first laminatelayer, the first laminate layer being a hollow cylinder formed of amaterial having a higher yield strength than the yield strength of thematerial forming the shell; and placing the first laminate layer overthe shell so as to cause the first laminate layer to apply a radialstress from the first laminate layer to the shell.
 23. The method ofclaim 22 wherein placing the first laminate layer includes applying anaxial force to the first laminate layer to cause the first laminatelayer to expand and move over the shell.
 24. The method of claim 22wherein placing the first laminate layer includes heating the firstlaminate layer before placing the first laminate layer over the shell.25. The method of claim 22 further comprising: providing a wire, thewire being formed of a material having a higher yield strength than theyield strength of the material forming the shell; and wrapping the wireover the first laminate layer so as to cause the wire to apply a radialstress from the wire to the first laminate layer.
 26. A method formaking a pressure-containing apparatus for a well completion equipment,comprising: providing well completion equipment; providing a shelladapted to be connected to a tubing and adapted to enclose the wellcompletion equipment and having a bore therethrough, the shell beingformed of a material having a yield strength; providing a wire, the wirebeing formed of a material having a higher yield strength than the yieldstrength of the material forming the shell; and wrapping the wire overthe shell so as to cause the wire to apply a radial stress from the wireto the shell and form a first laminate layer.
 27. The method of claim 26wherein wrapping the wire is performed with a tensile stress applied tothe wire during wrapping, the tensile stress being near the yieldstrength of the wire.
 28. The method of claim 26, further comprising:providing a second laminate layer, the second laminate layer being ahollow cylinder formed of a material having a higher yield strength thanthe yield strength of the material forming the shell; and placing thesecond laminate layer over the wire wrapped over the shell so as tocause the second laminate layer to apply a radial stress from the firstlaminate layer to the wire.
 29. A method for making apressure-containing apparatus for a well completion equipment,comprising: providing the well completion equipment; providing a shelladapted to be connected to a tubing and adapted to enclose the wellcompletion equipment and having a bore therethrough; providing a fiber,the fiber being formed of a ceramic material; wrapping the fiber overthe shell so as to cause the fiber to apply a radial stress from thefiber to the shell; and placing a molten metal around the fiber andallowing it to solidify to form a metal matrix composite material. 30.The method of claim 29 further comprising the step of heat treating thepressure-containing apparatus to form apparatus in compliance with NACEstandards.
 31. A method for making a pressure-containing apparatus for awell completion equipment, comprising: providing a tubular, the tubularbeing adapted to be connected to a well tubing and being formed of amaterial having a yield strength; providing a first laminate layer, thefirst laminate layer being a hollow cylinder formed of a material havinga higher yield strength than the yield strength of the material formingthe tubular; and placing the first laminate layer over the tubular so asto cause the first laminate layer to apply a radial stress from thefirst laminate layer to the tubular.
 32. The method of claim 31 furthercomprising: providing a wire, the wire being formed of a material havinga higher yield strength than the yield strength of the material formingthe shell; and wrapping the wire over the first laminate layer so as tocause the wire to apply a radial stress from the wire to the firstlaminate layer.
 33. A method for making a pressure-containing apparatusfor a well completion equipment, comprising: providing a tubular, thetubular being adapted to be connected to a well tubing and being formedof a material having a yield strength; providing a wire, the wire beingformed of a material having a higher yield strength than the yieldstrength of the material forming the tubular; and wrapping the wire overthe tubular so as to cause the wire to apply a radial stress from thewire to the tubular.
 34. The method of claim 33 wherein wrapping thewire is performed with a tensile stress applied to the wire duringwrapping, the tensile stress being near the yield strength of the wire.35. The method of claim 33, further comprising: providing a secondlaminate layer, the second laminate layer being a hollow cylinder formedof a material having a higher yield strength than the yield strength ofthe material forming the tubular; and placing the second laminate layerover the wire wrapped over the tubular so as to cause the secondlaminate layer to apply a radial stress from the first laminate layer tothe wire.
 36. A method for making a pressure-containing apparatus for awell completion equipment, comprising: providing a tubular adapted to beconnected to a well tubing and being formed of a material having a yieldstrength; providing a fiber, the fiber being formed of a ceramicmaterial; wrapping the fiber over the tubular so as to cause the fiberto apply a radial stress from the fiber to the tubular; and placing amolten metal around the fiber and allowing it to solidify to form ametal matrix composite material.
 37. The method of claim 36 furthercomprising the step of heat treating the pressure-containing apparatusto form apparatus in compliance with NACE standards.